Closure cap and container and method for making same

ABSTRACT

The invention is a twist-off closure cap and container assembly that provides the advantages of a tamper-indicating pilfer band with the attractive appearance of a metal crown cap. The closure cap is an overlay having a bright, metallic sheen and the coloration of brass or burnished steel. A printed design or logo reminiscent of a crown metal beer of soft drink cap may be printed on the overlay. The container is provided with an annular bulge that complements the pilfer ring of the closure cap. The closure cap also includes corrugated depressions, internal helical grooves and frangible bridging elements for detachably connecting the closure cap with the pilfer band. The pilfer band includes an interference lip that engages with a locking ring on the container so that when the closure cap is rotated with respect to the container the pilfer band stays with the container.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to tamper-indicating closures for containers and more particularly to a blow molding preform and a tamper-indicating plastic closure cap including a laminated film overlay.

BACKGROUND OF THE INVENTION

[0002] Crown caps are widely utilized for sealing glass bottle openings. These caps are typically formed of sheet metal and include a top, a side wall and a flared skirt. The skirt has a plurality of flutes that extend around the circumference at spaced intervals. When pressed onto an open end of a glass bottle having a bead about the opening, these flutes bend at the points of intersection between the bottle and the skirt, gripping the bead to seal the bottle. The circular, central top of the cap usually has a resilient lining on its internal surface composed of, for example, cork or a polyethylene derivative, which is placed against the end of the bottle to create a hermetic seal.

[0003] The crown cap has been used for some time to seal glass bottles, particularly for storing beverages bottled under pressure such as beer or carbonated soft drinks. Consumers generally associate the crown cap with containers for traditional, high-quality beverages. However, the crown cap is to difficult to open without the use of a bottle opener and practically impossible to reseal.

[0004] Previously disclosed twist-off, tamper-indicating closures include an upper closure cap having a skirt and an annular pilfer band depending from the skirt portion. The pilfer band is partially or completely detachably connected to the skirt portion by a series of circumferentially-spaced, frangible bridges or a scored sheet. The annular band portion typically remains on the neck of the container after it has been detached from the skirt portion.

[0005] One type of twist-off tamper-indicating closure is composed of a polymer material, such as high-density polyethylene (“HDPE”), and includes an interference-type pilfer band detachably secured to the closure by a frangible member. Containers for use with these interference-type pilfer bands have annular external locking rings on their neck portions, positioned beneath external screw threads on the outside of the container neck. The pilfer band includes a ledge for engaging the container locking ring. Specifically, the ledge is configured to move past the container locking ring when the closure is screwed onto the container to interferingly engage the container locking ring. When the closure is twisted off of the container, the frangible member breaks and the pilfer band remains on the container.

[0006] Traditional twist-off tamper-indicating closures are not entirely satisfactory because they do not normally accept and retain intricate printing. This is probably because interference-type pilfer bands and the closures that include them are usually composed of HDPE and polyethylene terephthalate (“PET”). Consequently, applying attractive decorative designs and logos to the exterior surface of the tamper-indicating closure is problematical.

[0007] The plastic bottling industry expands partially formed containers, known as “preforms,” in a stretch blow molding process to fabricate containers having threaded necks for mating with screw tops. The blow molding process permits high production rates and is capable of forming containers having narrow necks and voluminous bodies. However, the blow molding process, by itself, cannot produce screw threaded necks, which are better suited to fabrication by injection molding. While some hybrid processes are currently practiced, such as injection blow molding, the hybrid processes are not completely satisfactory because, among other things, they are much slower that traditional blow molding processes. Consequently, manufacturers typically produce or purchase quantities of injection-molded preforms that include screw-threaded tops, and then heat and expand the preforms to produce finished bottles by the stretch blow molding process.

[0008] The construction material for the preforms, which is the same as the finished plastic bottles, is usually dictated by the chemical composition of the liquid contents to be stored in the bottles and the temperature at which the bottles are to be filled. PET is an excellent material for stretch blow molding and is commonly used for carbonated beverage bottles. Related compositions, such as PETE, can also be used successfully. PET provides very good alcohol resistance and generally good chemical resistance. PET can be injection molded to produce preforms for stretch blow molding. PET is generally not suitable as a closure cap for carbonated beverages, which can generate significant internal pressure.

[0009] Polyvinyl chloride (“PVC”) and polycarbonate are acceptable construction materials for closure caps, with PVC being preferred. PVC is relatively strong without being objectionably brittle and is easily injection molded. PVC is also a good substrate for fine printing. However, the shapes of beverage closure caps make it difficult to print on the closure caps after they have been injection molded.

[0010] Another long-standing problem is that previously disclosed tamper-indicating closures simply do not look like metal crown closures. For whatever reason, consumers prefer crown closures for certain beverages, such as beer and carbonated soft drinks, and have consistently resisted the introduction of flexible plastic bottles and tamper-indicating closures for these beverages.

[0011] A need exists for a tamper-indicating closure equipped with an interference-type pilfer band that resembles a metal crown cap when installed on a flexible plastic beverage container. The new closure should be resealable and removable by hand or by bottle opener. Desirably, the new closure should twist off without exposing any sharp edges and should accept attractively printed designs and logos as are commonly seen on metal crown caps. Ideally, the new closure should fit a container having a shape that complements and disguises the silhouette of the interference-type pilfer band.

SUMMARY OF THE INVENTION

[0012] The invention is a twist-off closure cap that presents the appearance of a metal crown cap and includes an interference-type pilfer band. The closure cap includes an overlay that exhibits the metallic shine and color of brass or steel. The overlay surrounds the upper portion of the twist-off closure and, if properly prepared, can be printed with attractive logos and designs as are commonly seen on metal crown caps. The invention also provides a container that receives and complements the pilfer band.

[0013] The closure cap includes a generally cylindrical side wall and a flared skirt having a fluted outer surface and an inner surface having generally helical grooves. The pilfer band depends from the skirt portion and includes an inner surface that forms an interference lip. Frangible elements connect the pilfer band to the skirt portion.

[0014] The overlay is preferably dyed to resemble a bright, metallic bronze or steel finish. Portions of the overlay may be printed with fine artwork comparable to that seen on conventional crown caps for beer and carbonated beverage containers. The overlay is a laminated film structure that is bonded to the cap during an injection molding process.

[0015] The container includes a neck forming a dispensing opening and a neck surface surrounding the dispensing opening. A generally helical ridge extends from the neck surface and cooperates with the generally helical grooves of the closure cap so that the closure cap is raised with respect to the container when the closure cap is rotated in a counterclockwise direction. When properly installed, the interference lip of the pilfer band is engaged with a locking ring that extends from the container and, as a result, cannot rise when the twist-off cap is rotated. Consequently, rotating the closure cap in a counterclockwise direction breaks the frangible bridging elements, leaving the pilfer ring attached to the container. The container includes an annular bulge situated adjacent the locking rings, which blends with the silhouette of the pilfer band. Particularly when the container and the pilfer band are the same color, the pilfer band is inconspicuous.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is an elevation view of an assembly including a twist-off closure cap and an associated container;

[0017]FIG. 2 is an elevation view of the closure cap depicted in FIG. 1;

[0018]FIG. 3 is a cross-sectional view of the closure cap depicted in FIG. 1;

[0019]FIG. 4 is a partial cross-sectional view of the overlay depicted in FIG. 3; and

[0020]FIG. 5 is a cross-sectional view of a mold used in an injection molding process to produce the closure cap depicted in FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] In a preferred embodiment, the invention is twist-off closure cap and complementary container assembly 1 as depicted in FIG. 1. Assembly 1 includes container 50, which is a blow-molded polyethylene terephthalate (“PET”) preform specifically adapted for use with closure cap 10. As shown in FIG. 1, container 50 includes neck 52 surrounding dispensing opening 54 through which liquid contents may be filled and emptied. Neck 52 is surrounded by neck surface 56, generally helical ridges 58 and locking ring 60, which extends generally radially from neck surface 56. Ridges 58 cause closure cap 10 to rise or fall with respect to neck 52 when closure cap 10 is rotated on the end of neck 52 counterclockwise or clockwise, respectively. Locking ring 60 engages interference lip 30 (best seen in FIG. 3) of closure cap 10 so as to prevent interference lip 30 from rising when closure cap 10 is rotated counterclockwise. Annular bulge 62 is disposed about container 50 adjacent locking ring 60. Bulge 62 has a profile or silhouette that blends with and complements the silhouette of closure cap 10.

[0022] Container 50 is preferably composed of PET, which is widely used for flexible liquid storage containers. Container 50 may be clear or colored. Clear PET is popular for water containers. Green or amber PET resembles the type of glass commonly used for beer bottles. For storing carbonated beverages, the walls of container 50 are made relatively thicker than those of flexible plastic storage containers used for water and the like. For storing carbonated beverages, container 50 has a mass of 28 grams, as compared to a generally accepted 22 grams of mass for a standard flexible container.

[0023] Turning now to FIG. 2, closure 10 includes substrate 11 (best seen in FIG. 3), which is substantially covered by overlay 13. Generally circular skirt portion 14 surrounds circular top wall portion 12 and includes outer surface 25, which is crimped or corrugated to produce flutes. Each flute includes a substantially trapezoidally-shaped trough or depression 26 between a pair of crests 27.

[0024] Closure cap 10 also includes fracturable bridging elements 20, which are shown in FIG. 2. Each of the bridging elements 20 is a vertically-oriented sliver of material calculated to fracture when closure cap 10 is moved away from container 50. Alternatively, closure cap 10 may include a sheet having a plurality of scored sections (not shown) that are calculated to fracture upon movement of closure cap 10 away from container 50. Inside surface 24 includes generally helical grooves 28, which cooperate with ridges 28 to move closure cap 10 toward or away from container 50 when closure cap 10 is rotated.

[0025] As depicted in FIG. 2, bridging elements 20 detachably connect closure cap 10 to pilfer band 16, which is generally in the shape of a band surrounding bore 32. Neck surface 56 (best seen in FIG. 1) is sized to fit within bore 32. Pilfer band 16 includes interference lip 30 equipped with undercut 31 for engaging locking ring 60 when closure cap 10 is installed on container 50. In practice, this is accomplished by sliding bore 32 over the neck surface 56 until ridges 58 contact grooves 28 (best seen in FIG. 3) and then rotating closure cap 10 clockwise with respect to container 50 until locking ring 60 slips past interference lip 30 and engages undercut 31.

[0026]FIG. 3 is a cross-sectional view taken along plane X-X in FIG. 2 depicting the manner in which bridging elements 20 are formed on inside surface 24. Grooves 28 can be seen on inside surface 24.

[0027] Overlay 13, depicted in partial cross section in FIG. 4, is a laminated film structure that is bonded to substrate 11 (best seen in FIG. 3). Overlay 13 includes sealing film 40, which is preferably composed of the same material as substrate 11. Sealing film 40 may be composed of, for example, PVC or a polycarbonate. Laminated film structures suitable for use in the invention are commercially available from Multi-Color Corp. of Cincinnati, Ohio, or Label Tek of Yorkville, Ill., for example. In the depicted embodiments, sealing film 40 partially melts under controlled conditions so that it becomes welded at one surface to substrate 11. While melting or thermal welding is preferred, the invention may be successfully practiced by attaching sealing film 40 to substrate 11 by, for example, solvent welding, ultrasonic welding or applying a heat-setting adhesive.

[0028] In contrast, surface 42 does not melt or become significantly distorted while surface 41 is attached to substrate 11. Preferably, surface 42 has been previously attached to surface 43 of printed film 44 by thermal welding, ultrasonic welding, solvent welding, adhesion or some similar process and provides stable support for printed film 44. Varnish film 47, which protects against thermal shock and mechanical abrasion, is located on printing surface 45.

[0029] Film 44 may be dyed or printed to resemble a bright, metallic surface (such as bronze or steel), a painted surface or a printed surface. Preferably, as shown in FIG. 2, portion A is printed to resemble a painted metal crown cap and portion B is dyed or printed to resemble an unfinished edge of a metal crown cap. Portion C is preferably clear or the same color as a container intended for mating with closure cap 10.

[0030] The invention is also a process for manufacturing closure cap 10 and container 50. A vacuum pick-up tube (not shown) is used to pick up overlay 13 and place overlay 13 in the cavity of mold 80, which is depicted in closed position in FIG. 5. Although only one mold 80 is depicted, it should be understood that a number of such molds may be operated simultaneously. Vacuum conduits 86 hold overlay 13 in position against upper piece 81 while mold 80 is closed by moving lower piece 83 and center piece 85 toward upper piece 81, and moving side pieces 82, 84 inwardly toward each other.

[0031] Mold 80 is heated using conventional methods. However, a coolant stream flows into inlet port 88 through a channel (not shown) within upper piece 81 and exits through outlet port 89. The coolant stream cools upper piece 81 and printed film 44 so that printing surface 45 is protected from the full operating temperature of the cavity of mold 80. Other coolant streams (not shown) may be used to cool the other mold pieces 82-85 so as to promote cooling in cavity 92 in order to speed the molding process

[0032] With mold 80 in closed position, hot runner 87 is inserted through conduit 90 in lower piece 83 and through conduit 91 through center piece 85. Molten PVC is injected into the cavity of mold 80 under a pressure in the range of about 160,000 to about 240,000 pounds per square inch at a precisely controlled temperature in the range of about 180 to about 200 degrees F., which temperature causes sealing film 40 of overlay 13 to bond to attaching surface 42. When the molten PVC in the cavity of mold 80 sets, which typically occurs in about 2 to about 3 seconds, welding surface 41 bonds to attaching surface 42 of overlay 13. However, because printing surface 45 is protected from this temperature by the coolant stream, it remains at a temperature below the operating temperature of the mold cavity. Printed matter at printing surface 45 survives the injection molding process and emerges from mold 80 intact and without significant deformation. Exposed dyed material at printing surface 45 emerges from mold 80 with a bright, metallic sheen.

[0033] Upper mold part 81 is retracted generally vertically after closure cap 10 has cooled sufficiently to retain its shape. Left and right mold parts 82, 84 are retracted laterally. Lower mold part 83 is retracted downwardly. Finally, closure cap 10 is ejected from core mold part 85. Although undercuts associated with bridging elements 18 hinder the release of closure cap 10 from core mold part 85, PVC is sufficiently resilient to permit closure cap 10 to deform during ejection and return to the shape of mold 80. Closure cap 10 is cooled to room temperature and stored until needed.

[0034] The finished container is produced by subjecting preform container 50 to conventional blow molding processes. Subsequently, the finished container is filled with an appropriate beverage, such as beer or a carbonated soft drink, and closure cap 10 is pressed onto the finished container in a conventional rotary press causing ridges 58 to meet grooves 28. Closure cap 10 is then rotated clockwise with respect to the finished container in order to advance interference lip 31 over locking ring 60 and engage interference lip 30 with undercut 31.

[0035] The invention provides an improved closure cap for flexible plastic containers that resembles the traditional metal crown cap found on beer bottles and provides the added advantage of a tamper-indicating interference-type pilfer band. The closure cap can be removed by hand or by bottle opener and, in either case, is resealable. The container of the present invention receives the closure cap and provides a matching silhouette for the pilfer band. The pilfer band and the mating container present the appearance of being a single unit.

[0036] Although descriptions of preferred embodiments and specific examples are provided above in order to better communicate the invention, the invention is not limited by these descriptions or examples. To the contrary, the scope of the invention is defined by the appended claims. 

That which is claimed:
 1. A twist-off closure cap, comprising: a polymer substrate including a circular top wall and a generally circular skirt that depends from the top wall, the skirt including an outer surface having circumferentially arranged depressions and an inner surface having generally helical grooves; a laminated film overlay having a metallic surface sheen molded on the polymer substrate; a pilfer band depending from the skirt portion and having an inner surface that includes an interference lip; and frangible bridging elements detachably connecting the pilfer band to the skirt portion.
 2. The closure cap of claim 1, in which the laminated film overlay includes a sealing film and a printed film.
 3. The closure cap of claim 2, in which the laminated film overlay includes a varnish film.
 4. The closure cap of claim 1, in which the substrate, the sealing film and the printed film are composed of polyvinyl chloride.
 5. The closure cap of claim 1, in which the substrate, the sealing film and the printed film are composed of polycarbonate.
 6. The closure cap of claim 1, in which the overlay resembles a crown metal bottle cap.
 7. A container that comprises: a neck forming a dispensing opening and a neck surface surrounding the dispensing opening; a generally helical ridge extending from the neck surface; a locking ring extending from the container; and an annular bulge situated adjacent the locking ring.
 8. The container of claim 7, which is composed of polyethylene terephthalate.
 9. The container of claim 7, which is a preform suitable for use in a blow molding process.
 10. A twist-off closure cap and container assembly, comprising: a twist-off closure cap including a polymer substrate that includes a circular top wall and a depending, generally circular skirt that includes an outer surface having circumferentially arranged depressions and an inner surface having generally helical grooves; a laminated film overlay having a metallic surface sheen molded on the polymer substrate; a break-away pilfer band depending from the skirt portion, the pilfer band having an inner surface that includes an interference lip; and frangible bridging elements detachably connecting the pilfer band to the skirt portion; and a container including a neck forming a dispensing opening and a neck surface surrounding the dispensing opening; a generally helical ridge extending from the neck surface; a locking ring extending from the container; and an annular bulge situated adjacent the locking ring.
 11. The closure cap of claim 10, in which the laminated film overlay includes a sealing film and a printed film.
 12. The closure cap of claim 11, in which the laminated film overlay includes a varnish film.
 13. The closure cap of claim 10, in which the substrate, the sealing film and the printed film are composed of polyvinyl chloride.
 14. The closure cap of claim 10, in which the substrate, the sealing film and the printed film are composed of polycarbonate.
 15. The closure cap of claim 10, in which the overlay resembles a crown metal bottle cap.
 16. The container of claim 110, which is composed of polyethylene terephthalate.
 17. A method of manufacturing a closure cap, which comprises: abutting a plurality of mold parts to form an injection molding cavity; positioning a laminated film overlay within the injection molding cavity; and injecting molten polymer into the injection molding cavity.
 18. The method of claim 17, in which the laminated film overlay includes a sealing film and a printed film.
 19. The method of claim 18, in which the laminated film overlay includes a varnish film.
 20. The method of claim 17, in which the substrate, the sealing film and the printed film are composed of polyvinyl chloride.
 21. The method of claim 17, in which the substrate, the sealing film and the printed film are composed of polycarbonate.
 22. The method of claim 17, in which the overlay is secured within the injection molding cavity by negative pressure within a vacuum conduit that communicates with the molding cavity.
 23. The method of claim 17, in which at least one of the mold parts is cooled by a coolant stream flowing through a channel in the mold part. 